From: Reza Toghraee (reza@toghraee.com)
Date: Tue Oct 14 2008 - 04:33:53 ART
Yes I did, and also I saw that if you put "ip ospf cost 65535" on the
loopback and the transit link, the neighbor router will see the route
with metric of 131070.
Also I connected 3 routers together with OSPF, with interfaces having
"ip ospf cost 65535". In the last router I saw the loopback of 1st
router with metric of 196605 (3*65535)
Now the question is that the Metric field in LSA packet is 16 bits,
how it carries more than 16 bit (65535) ?????
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Gary
Duncanson
Sent: Tuesday, October 14, 2008 10:25 AM
To: Richard L. Pickard
Cc: Cisco certification
Subject: Re: OSPF Question, how to prefer inter area routes, over intra area
Seems to make more sense. I did wonder that it should actually work. Thanks
Richard
----- Original Message -----
From: "Richard L. Pickard" <richardlpickard@hotmail.com>
To: "Gary Duncanson" <garyduncanson@btinternet.com>
Sent: Monday, October 13, 2008 9:31 PM
Subject: Re: OSPF Question, how to prefer inter area routes, over intra area
>
>
> If you have only one working link from A - to - B data will take that
> path even if cost = 65535
>
> I think the guy who did the original post is probably not using real
> routers
>
>
> R
>
>
> ----- Original Message -----
> From: "Gary Duncanson" <garyduncanson@btinternet.com>
> To: "Scott Morris" <smorris@internetworkexpert.com>
> Cc: "Cisco certification" <ccielab@groupstudy.com>
> Sent: Monday, October 13, 2008 2:01 PM
> Subject: Re: OSPF Question, how to prefer inter area routes, over intra
> area
>
>
>> That's interesting. I figured 65535 as the highest would actually work if
>> that's all you have going for you. I haven't tested this myself just
>> logic here.
>>
>> Is it like admin distance 255 then in some sense i.e unbelievable or just
>> don't use?
>> ----- Original Message -----
>> From: "Scott Morris" <smorris@internetworkexpert.com>
>> To: "'Reza Toghraee'" <reza@toghraee.com>
>> Cc: <ccielab@groupstudy.com>
>> Sent: Monday, October 13, 2008 3:18 PM
>> Subject: RE: OSPF Question, how to prefer inter area routes, over intra
>> area
>>
>>
>>> Correct. You are setting your links cost (thus the router
>>> advertisements)
>>> to the maximum value which basically says "I'm here, but don't use me!"
>>>
>>> -----Original Message-----
>>> From: Reza Toghraee [mailto:reza@toghraee.com]
>>> Sent: Monday, October 13, 2008 8:01 AM
>>> To: 'Scott Morris'
>>> Cc: ccielab@groupstudy.com
>>> Subject: RE: OSPF Question, how to prefer inter area routes, over intra
>>> area
>>>
>>> Yes I manipulated, and changed the cost of other links to a higher
>>> value.
>>> But I didn't check the "sh ip ospf virt". Now I understand why it
>>> doesn't go
>>> on virtual link by default. BECAUSE the COST of VIRTUAL-LINKS is
>>> significantly higher.
>>>
>>> 1 more question : What does "ip ospf cost 65535" mean? Does it mean
>>> that NO
>>> TRAFFIC will pass the link even if this is the only operational link?
>>>
>>> Regards
>>> Reza
>>>
>>>
>>> -----Original Message-----
>>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>>> Scott Morris
>>> Sent: Monday, October 13, 2008 3:52 PM
>>> To: 'Reza Toghraee'
>>> Cc: ccielab@groupstudy.com
>>> Subject: RE: OSPF Question, how to prefer inter area routes, over intra
>>> area
>>>
>>> Once you have your virtual link, you'll notice that the cost to the
>>> routes
>>> is significantly higher though. Have you tried manipulation in this
>>> sense?
>>> (sh ip ospf virtual-link)
>>>
>>> -----Original Message-----
>>> From: Reza Toghraee [mailto:reza@toghraee.com]
>>> Sent: Monday, October 13, 2008 6:40 AM
>>> To: smorris@internetworkexpert.com
>>> Cc: ccielab@groupstudy.com
>>> Subject: RE: OSPF Question, how to prefer inter area routes, over intra
>>> area
>>>
>>> It's a Lab scenario, I crated myself of course its amazing ;)
>>>
>>> I found this Method, and its working
>>>
>>> 1) R3 peers with R2 over a virtual link on Area23
>>> 2) R1 peers with R3 over a virtual link on Area13
>>> 3) R1 puts ospf cost 100 on its 64K link to R2.
>>>
>>> So R1 receives R2' Loopback interface over its 64K link and also from
>>> Virtual link from R3. Both as intra-area.
>>> By default it should prefer the virtual link, and if not we can use ip
>>> ospf
>>> cost to change metrics.
>>>
>>>
>>> -----Original Message-----
>>>
>>> You'll ALWAYS get intra-area over inter-area. That's the way the spec
>>> is
>>> written, and it just plain makes sense. :)
>>>
>>> Was it intentional to make the slowest path the "backbone" of your OSPF
>>> network?
>>>
>>> Scott
>>>
>>> -----Original Message-----
>>> 174.1.13.0/24
>>> _____ __________________________ _____
>>> | R1| | | | R2|
>>> |___|---| A R E A 0 |--------|___|
>>> | | This link is a 64K | |
>>> | |__________________________| |
>>> | ____|______
>>> __|__________ | |
>>> | | | |
>>> | AREA13 | _______| |
>>> | | 174.1.31.1 V13 | |
>>> | 10Mbps | | |
>>> |____________| | A R E A 23 |
>>> | | |
>>> __|__ |_________________| 10Mbps BW |
>>> | R3| | |
>>> |___|-------|___________________________________|
>>> 174.1.43.4 /24 V 43
>>>
>>>
>>>
>>> R2 is advertising it Looback in OSPF AREA 0 ,with network command.
>>> R1 will route through the AREA 0, on 64K Link to reach R2' Loopback 0.
>>>
>>> Question 1 : how to make R1, route through R3 on Area 13, and Area 23 to
>>> reach R2' Loopback ?
>>>
>>> What I tried :
>>> 1) I tried to use distance on the routes coming from R2, to change them
>>> to
>>> 130, but seems the OSPF first chooses the InterArea route over intra
>>> area,
>>> then applies the distance.
>>> 2) I used a distribution-list on R1 to filter the routes coming from R2.
>>> Its
>>> working but if the Link between R1,R3 is disconnected, then R1 cannot
>>> reach
>>> R2' Loopback
>>>
>>>
>>> Question 2: R2 Advertises its Loopback with Redistribution as E1.
>>>
>>> What I tried :
>>>
>>> 1) I tried to change the costs on 64K Link to very high. But I don't
>>> remember it worked or not.
>>>
>>>
>>> Waiting for your solutions.
>>> Reza Toghraee
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>> _______________________________________________________________________
>>> Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>> _______________________________________________________________________
>>> Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>> _______________________________________________________________________
>>> Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
Blogs and organic groups at http://www.ccie.net
This archive was generated by hypermail 2.1.4 : Sat Nov 01 2008 - 15:35:20 ARST